The present invention relates to an improved in-feed method for moving a series of bags with gusseted tops and loaded with loose materials, such as for example resin granules and the like, wherein the gusseted tops are initially closed but not yet finally sealed, as the bags are individually being introduced in line into a machine, as for example a final bag closing station utilizing sewing or heat sealing means. The present invention has been found to be particularly useful in the loaded, gusseted bag handling art, especially in the transferring of the bags from a bag reforming station to the final bag closing station and especially in association with an in-feed device having tapered, pivoting, opposed in-feed arms, and hence will be discussed with particular reference thereto, although the method of the present invention is not limited to such applications.
Several types of in-feed devices and methods have been known and used before, and typical examples thereof in the bag handling art are shown in U.S. Pat. No. 3,687,790, issued Aug. 29, 1972 to T. Wehren et al; U.S. Pat. No. 3,691,968, issued Sept. 19, 1972 to Schnepf; U.S. Pat. No. 2,097,447, issued Nov. 2, 1937 to Cundall et al; and U.S. Pat. No. 2,725,168, issued Nov. 29, 1955 to Lindstaedt et al.
However, it has been found that the bags in being processed through the in-feed devices of the prior art often or at least on occasion became misaligned or wrinkled, so that when they were closed in the sewing or sealing station, the closures were improperly and/or inaccurately made or made askew. Even in the in-feed device and method disclosed in the parent application hereof (now U.S. Pat. No. 3,875,726), which represented a substantial advance in the art over the aforelisted prior art patents, the loaded bags with their reformed gusseted tops still on occasion became misaligned, so that when they were closed in the sewing or sealing station, the closures were improperly and/or inaccurately made or made askew, particularly with certain types of loads in the bags and certain types of bag material.
In particular, when the bags were carrying a load of loosely filled materials or cargo such as for example chemical granules and the like, and/or when the bag material was relatively supple and flexible with little body rigidity, a bag top with its gusseted top reformed or closed would on occasion become partially unformed or unmade under the action of the load shifting forward when the bag was being pushed from behind by a pusher mechanism such as for example the multiple finger pushers disclosed in the Olinkraft U.S. Pat. No. 3,796,300. The shifting load would, it is believed, move forward in the bag, especially at the top thereof, creating an outward force against the leading face of the top thereof, causing the mechanically unrestrained gusseted sides of the top to puff-out thereby make reforming of gusset difficult if not impossible. Accordingly, when the bag top entered and passed through the in-feed device, the top would be mis-aligned when presented to the sealing station.
In contrast, the present invention prevents the possibility of such an occurrence by mechanically or physically restraining the bag on all four sides while heretofore the front side of the bag was completely unrestrained. Moreover, the present invention achieves this additional restraint, not by means of a separate involved mechanical device but rather in a most straightforward, economical and, in retrospect, simple manner, that is by moving a filled bag forward in at least the latter stages of processing when in face-to-face contact with the preceding filled bag, the latter serving to restrain the front of the former in their pushing engagement.
This preceding bag restraint in cooperation with the restraints provided by opposing guides on opposite sides of the machine and the rear restraint provided by the pusher itself results in the moving bag being restrained on all four sides, a unique and most desirable situation.
Were it not for the method of the present invention, one would need to provide either an additional operator or a separate moving mechanical device, with all its inherent disadvantages, to engage the front side of the bag as the bag is moved in order to achieve the same desirable constraining results of the present invention.
In combination with the four-sided constraint aspects of the present invention, the most preferred embodiment of the present method includes the use of an in-feed mechanism utilizing dual, opposed, moving belts whose supports are not static but instead, initially present a tapered configuration at the inlet portion as the bag enters it and subsequently, after the bag enters the device, presents a closed, parallel configuration as the supports are pivoted together. The combined action of both allows the in-feed station of the machine to properly guide, align and hold the bag, for proper and accurate presentation of each bag for the final closing operation.
Thus the restraining action of the present invention on the front side of the bag as the bag is moved in engagement against the preceding bag, thereby pushing the leading bag during sequential, intermittant movements of the bags through the machine, all in combination with the movement and action of the tapered, pivoting in-feed arms described more fully below and in the parent application, produces, it is believed, far greater reliability in bag sealing than ever heretofore achieved.
Thus, the present invention provides the solution to the problems of prior systems with a straightforward, reliable and relatively simple improved system without any need for hand labor or additional complex mechanical mechanisms.
Additionally, as explained more fully below, besides serving as a simple in-feed system, the present invention can also be used to perform the final reforming step for the gusseted bag top.
Finally, the in-feeding operation is performed without the need of doing it at an unreasonably high speed because of combining the final reforming and in-feeding functions in a single stage, further enhancing the reliability of performance.